External fixation compared to intramedullary nailing of tibial fractures in the rat

The effect of soft tissue defect on callus formation in Kunming mice different tibial injury models.. [DOI: 10.21203/rs.3.rs-2006802/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Objective: To investigated the highly replicable bone injury model and the effect of soft tissue defect on bone repair. Methods: Fifty 6-week-old female kunming mice were randomly divided into 5 groups, and the 4 groups of them underwent fracture or bone defect surgery on the right tibia with or without tibialis anterior muscle defect respectively. The right injured tibias and heart blood were collected on day 10 after operation for Micro-CT, histological and ELISA analysis respectively. The fifth group was control group，and the cardiac blood was collected at the same time for ELISA.RESULTS: Micro-CT and histological examination indicated that our modelling approach could successfully provide different animal models of open bone injury. Micro-CT showed a significant increase in the ratio of bone volume to tissue volume (BV/TV, %) after soft tissue defect in different bone injury models compared to the soft tissue preserved group. Histomorphometric analysis demonstrated a significant increase in the amount of total bone callus, cartilage callus and fibrous tissue after soft tissue defects, while the amount of hard callus was significantly reduced. Immunohistochemical analysis showed higher levels of CYR61 and VEGFR2 after soft tissue defect. ELISA results revealed no significant difference in IL-1β levels between the soft tissue preserved and soft tissue defect groups. HE staining also confirmed no significant difference in the degree of inflammatory cell infiltration after soft tissue defect.Conclusion: The above models were simple，highly reproducible, and provided reliable animal models for studying the bone healing. We inferred that mechanical stability played an important role in the process of bone healing, and the soft tissue around the injury site mainly provided fixation and protection.

Comparison of intramedullary nailing fixation and percutaneous locked plating fixation for the treatment of proximal tibial fractures: A meta-analysis

OBJECTIVE

This meta-analysis aimed to systematically compare the clinical outcomes of intramedullary nailing (IMN) fixation and percutaneous locked plating (PLP) fixation in the treatment of proximal tibial fractures.

METHODS

We searched PubMed, Embase, Cochrane library, China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), and Wan Fang to select relevant articles up to March 29, 2020 without language limit. Continuous variables were estimated by weighted mean difference (WMD) with a 95% confidence interval (CI) and dichotomous outcomes were calculated by relative risk (RR) with 95% CI. Moreover, heterogeneity analysis was evaluated. Furthermore, publication bias assessment and sensitivity analysis were conducted. Stata 11.0 software was used to perform the statistical analysis.

RESULTS

Ten studies involving 667 cases (321 from IMN fixation group and 346 from PLP fixation group) were included. The type of fractures involved in the included articles was extra-articular proximal tibia fractures. IMN fixation method achieved significantly shorter union time (WMD = -2.88, 95% CI: -3.23 to -2.53, p < 0.001) and full weight-bearing time (WMD = -2.81, 95% CI: -3.64 to -1.97, p < 0.001) than PLP fixation method. Meanwhile, IMN fixation resulted in lower risks of infection (RR = 0.50, 95% CI: 0.27 to 0.91, p = 0.02) and total complications (RR = 0.36, 95% CI: 0.22 to 0.60, p < 0.001) than PLP fixation. No significant differences were found in the incidence of nonunion (p = 0.33), malunion (p = 0.38), and osteofascial compartment syndrome (OCS, p = 0.62) between the two groups.

CONCLUSIONS

Compared to PLP fixation, IMN fixation had several advantages in treating proximal tibial fractures, including the short time of union and full weight-bearing, as well as a low risk of infection and total complications.

Morphine Exacerbates Postfracture Nociceptive Sensitization, Functional Impairment, and Microglial Activation in Mice

BACKGROUND

Emerging evidence suggests that opioid use immediately after surgery and trauma may worsen outcomes. In these studies, the authors aimed to determine whether morphine administered for a clinically relevant time period (7 days) in a tibia fracture orthopedic surgery model had adverse effects on postoperative recovery.

METHODS

Mice were given morphine twice daily for 7 days after unilateral tibial fracture and intramedullary pin fixation to model orthopedic surgery and limb trauma. Mechanical allodynia, limb-specific weight bearing, gait changes, memory, and anxiety were measured after injury. In addition, spinal cord gene expression changes as well as glial activation were measured. Finally, the authors assessed the effects of a selective Toll-like receptor 4 antagonist, TAK-242, on nociceptive and functional changes after injury.

RESULTS

Tibial fracture caused several weeks of mechanical nociceptive sensitization (F(1, 216) = 573.38, P < 0.001, fracture + vehicle vs. sham + vehicle, n = 10 per group), and this change was exacerbated by the perioperative administration of morphine (F(1, 216) = 71.61, P < 0.001, fracture + morphine vs. fracture + vehicle, n = 10 per group). In additional testing, injured limb weight bearing, gait, and object location memory were worse in morphine-treated fracture mice than in untreated fracture mice. Postfracture expression levels of several genes previously associated with opioid-induced hyperalgesia, including brain-derived neurotrophic factor and prodynorphin, were unchanged, but neuroinflammation involving Toll-like receptor 4 receptor-expressing microglia was observed (6.8 ± 1.5 [mean ± SD] cells per high-power field for fracture + vehicle vs. 12 ± 2.8 fracture + morphine, P < 0.001, n = 8 per /group). Treatment with a Toll-like receptor 4 antagonist TAK242 improved nociceptive sensitization for about 2 weeks in morphine-treated fracture mice (F(1, 198) = 73.36, P < 0.001, fracture + morphine + TAK242 vs. fracture + morphine, n = 10 per group).

CONCLUSIONS

Morphine treatment beginning at the time of injury impairs nociceptive recovery and other outcomes. Measures preventing glial activation through Toll-like receptor 4 signaling may reduce the adverse consequences of postoperative opioid administration.

Modulation of fixation stiffness from flexible to stiff in a rat model of bone healing

Background and purpose - Constant fixator stiffness for the duration of healing may not provide suitable mechanical conditions for all stages of bone repair. We therefore investigated the influence of stiffening fixation on callus stiffness and morphology in a rat diaphyseal osteotomy model to determine whether healing time was shortened and callus stiffness increased through modulation of fixation from flexible to stiff. Material and methods - An external unilateral fixator was applied to the osteotomized femur and stiffened by decreasing the offset of the inner fixator bar at 3, 7, 14, and 21 days after operation. After 5 weeks, the rats were killed and healing was evaluated with mechanical, histological, and microcomputed tomography methods. Constant fixation stiffness control groups with either stiff or flexible fixation were included for comparison. Results - The callus stiffness of the stiff group and all 4 experimental groups was greater than in the flexible group. The callus of the flexible group was larger but contained a higher proportion of unmineralized tissue and cartilage. The stiff and modulated groups (3, 7, 14, and 21 days) all showed bony bridging at 5 weeks, as well as signs of callus remodeling. Stiffening fixation at 7 and 14 days after osteotomy produced the highest degree of callus bridging. Bone mineral density in the fracture gap was highest in animals in which the fixation was stiffened after 14 days. Interpretation - The predicted benefit of a large robust callus formed through early flexible fixation could not be shown, but the benefits of stabilizing a flexible construct to achieve timely healing were demonstrated at all time points.

Is There an Impact of Concomitant Injuries and Timing of Fixation of Major Fractures on Fracture Healing? A Focused Review of Clinical and Experimental Evidence

OBJECTIVE

This review aims to summarize current knowledge regarding the underlying patho-mechanisms of delayed fracture healing in polytraumatized patients.

DATA SOURCES AND STUDY SELECTION

The following search terms were used: "fracture", "hemorrhage," "chest trauma," "inflammation," "inflammatory response," "fracture healing," "delayed healing," "nonunion," "fracture stabilisation," "intramedullary nailing," "external fixation," "early total care," and "damage control." Medline, Embase, and Cochrane Library were searched for studies published between January 1, 1990 through March 30, 2014. Of 1322 publications, 68 were included in the current summary.

CONCLUSION

Concomitant injuries and the strategy for fracture stabilization seem to affect bone metabolism and fracture healing. Among the relevant patho-mechanisms, interactions between the local and systemic inflammatory response seem to play a role. However, the consequences of fracture fixation strategies in case of severe concomitant injuries on local inflammation and bone healing remain unknown.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Intramedullary nailing after external fixation of the femur and tibia: a review of advantages and limits

PURPOSE AND METHODS

External fixation is a safe option for stabilisation of extremity lesions in the polytraumatised patient as well as in fractures with severe soft tissue damage. Nevertheless, long-term-complications are to be expected when external fixation is chosen as a definitive treatment. The purpose of this review article is twofold: primarily, to define the rationale of a procedural change from an external fixator to an intramedullary nail; secondarily, to assess the possible advantages and pitfalls of a single- or two-staged procedure.

RESULTS AND CONCLUSIONS

External fixation of the femur is recommended in multiply injured patients who are critically ill to avoid an additional inflammatory response caused by the surgical trauma of primary nailing. The conversion towards nailing must be done as soon as the clinical condition of the patient has been stabilised. Stable polytraumatised patients do not benefit from initial stabilisation with an external fixator and should immediately be treated with a definitive osteosynthesis. In tibial fractures, external fixation followed by intramedullary nailing is recommendable in fractures with severe soft tissue injuries. Conversion should be done as soon as the soft tissues allow before pin-tract infections occur and performed in a one-staged procedure.

Immobilization contributes to exaggerated neuropeptide signaling, inflammatory changes, and nociceptive sensitization after fracture in rats

A tibia fracture cast immobilized for 4 weeks can induce exaggerated substance P and calcitonin gene-related peptide signaling and neuropeptide-dependent nociceptive and inflammatory changes in the hind limbs of rats similar to those seen in complex regional pain syndrome (CRPS). Four weeks of hind limb cast immobilization can also induce nociceptive and vascular changes resembling CRPS. To test our hypothesis that immobilization alone could cause exaggerated neuropeptide signaling and inflammatory changes, we tested 5 cohorts of rats: 1) controls; 2) tibia fracture and hind limb casted; 3) hind limb casted, no fracture; 4) tibia fracture with intramedullary pinning, no cast; and 5) tibia fracture with intramedullary pinning and hind limb casting. After 4 weeks, the casts were removed and hind limb allodynia, unweighting, warmth, edema, sciatic nerve neuropeptide content, cutaneous and spinal cord inflammatory mediator levels, and spinal c-Fos activation were measured. After fracture with casting, there was allodynia, unweighting, warmth, edema, increased sciatic nerve substance P and calcitonin gene-related peptide, increased skin neurokinin 1 receptors and keratinocyte proliferation, increased inflammatory mediator expression in the hind paw skin (tumor necrosis factor-α, interleukin [IL]-1β, IL-6, nerve growth factor) and cord (IL-1β, nerve growth factor), and increased spinal c-Fos activation. These same changes were observed after cast immobilization alone, except that spinal IL-1β levels were not increased. Treating cast-only rats with a neurokinin 1 receptor antagonist inhibited development of nociceptive and inflammatory changes. Four weeks after fracture with pinning, all nociceptive and vascular changes had resolved and there were no increases in neuropeptide signaling or inflammatory mediator expression.

PERSPECTIVE

Collectively, these data indicate that immobilization alone increased neuropeptide signaling and caused nociceptive and inflammatory changes similar to those observed after tibia fracture and casting, and that early mobilization after fracture with pinning inhibited these changes. Early limb mobilization after fracture may prevent the development of CRPS.

[Effect of intramedullary reaming and nailing on the production of growth factors in the femur fracture callus in rats]

INTRODUCTION

Many studies have been conducted to determine the different effects that reaming or intramedullary nailing have on fracture healing, but there is no evidence in the literature of the effect of intramedullary reaming on osteogenesis. We performed a prospective study to analyse the effect of intramedullary reaming and nailing on the production of growth factors during the process of fracture healing in the femur of rats.

MATERIAL AND METHODS

A transverse mid-shaft non-comminuted femur fracture was produced in 64 rats; 34 rats did not receive any treatment, and a standardized surgical procedure was performed on 30 rats, by exposing the left knee, reaming the medullary canal from distal to proximal, and then fixing the fracture with a steel pin. The rats were sacrificed at the 24th hour, 4th, 7th and 15th days after the fracture. The amount of growth factors that appeared in the callus fracture was measured using histopathology studies. The primary categorical variables analysed were PDGFA, TGF2 and TGFβ-R2. These variables were analysed in each group at the different sacrifice times.

RESULTS

The results of the primary variables of the study, stratified by the time until sacrifice, showed no statistically significant differences.

DISCUSSION

Even if the presence of an intramedullary wire facilitates the fracture repair and the stabilising the bridge of bone between both edges of the fracture site, no evidence was found that reaming changes the expression of the growth factors studied (PDGFA, TGFβ-R2 and TGFβ2) during the callus formation in rats.

Conversion from external fixator to intramedullary nail causes a second hit and impairs fracture healing in a severe trauma model

In poly-traumatic patients, second hits are known to potentiate the posttraumatic systemic inflammatory response, thus increasing the risk of multi-organ dysfunction. In accordance with "damage control orthopaedic surgery" principles, fractures are initially treated with external fixators, which are replaced by internal osteosynthesis once the immunological status of the patient is considered stable. Recently, we demonstrated that a severe trauma impaired the healing of fractures stabilized by external fixation during the entire healing period. The question arose, whether switching to intramedullary nailing increases the inflammatory response in terms of a second hit, leading to a further impairment of bone healing. Wistar rats received a femoral osteotomy stabilized by an external fixator. Simultaneously half of the rats underwent an additional thoracic trauma. After 4 days, the external fixator was replaced by an intramedullary nail in half of the rats of the two groups. The inflammatory response was evaluated by measuring serum C5a levels. Fracture healing was determined by three-point-bending, µCT, and histomorphometry. The thoracic trauma significantly increased C5a concentrations 6, 24, and 72 h after the second surgical intervention. After 40 days, conversion to intramedullary nailing considerably decreased the flexural rigidity of the callus, with no significant differences between rats with or without thoracic trauma. After 47 days, flexural rigidity in rats subjected to conversion remained decreased compared to animals solely treated by external fixation, particularly in combination with blunt chest trauma. The results indicate that accumulation of second hits after multiple injuries could lead to aggravation of the fracture healing outcome.

The influence of compression on the healing of experimental tibial fractures

PURPOSE

Experimental studies of the effects of various mechanical conditions and stimuli on bone healing have disclosed an improvement potential in bone fracture mineralization and biomechanical properties. We therefore evaluated the effect of a clinically practicable application of a mechanical compressive interfragmentary stimulus on the healing of experimental tibial diaphyseal fractures.

METHODS

Sixty Male rats received a standardized tibial shaft osteotomy stabilized with a unilateral external fixator with a zero interfragmentary distance, and then randomly assigned to the compression (N=20), control (N=20) or distraction (N=20) group. From days 4 to day 14, the external fixator was either tightened (compression group) or loosened (distraction group) once daily to gradually induce a total axial displacement of the external fixator pin clamps of 1.25 mm. Evaluation at 30 and 60 days post-osteotomy included radiography, dual-energy X-ray absorptiometry (DXA), quantitative CT and mechanical testing.

RESULTS

All fractures healed radiographically with sparse callus. At 60 days, the compression and control groups exhibited significantly less amount of mineralized callus in terms of DXA measured callus area and bone mineral content (BMC) compared to the distraction group. These groups also demonstrated a smaller volume of low-mineralized bone tissue (callus) and a larger volume of highly mineralized bone tissue (cortical bone) measured by QCT than in the distraction group. Both mechanical strength and stiffness was significantly higher in the compression and control groups than in the distraction group at 60 days.

DISCUSSION

Compression did not enhance fracture healing in terms of mineralization, bending strength, or stiffness at the time of union, compared with the control condition. The compression and control groups exhibited improved healing in terms of mechanical strength and stiffness and a more mature callus mineralization compared with the distraction group.

The Effect of timing of conversion from external fixation to secondary intramedullary nailing in experimental tibial fractures

Diaphyseal tibial fractures with initial temporary external fixation (EF) are usually converted to intramedullary nailing (IMN) within 2 weeks, and no consensus on the optimal conversion time point exists. Current clinical practice is mainly based on estimation of the risk of postoperative infection. This is the first investigation of the effect of timing of such conversion on fracture healing. Forty male rats received a standardized tibial shaft osteotomy and EF. The animals were then randomly assigned to conversion to IMN at either 7 (group A, N = 10), 14 (group B, N = 10), or 30 (group C, N = 10) days after initial fixation. Group D (N = 10) served as a control group without conversion. Evaluation at 60 days included X-ray, DXA, and mechanical testing. Group A had significantly increased bone mineral content and callus area compared to the control group. Groups B and C showed significantly inferior mechanical bending strength and rigidity compared to both group A and the control group (D). The timing of the conversion procedure has a significant effect on fracture healing. Early conversion procedure did not improve healing compared to control, but was advantageous compared to late conversion (at 2 or 4 weeks) with higher mineralization and superior biomechanical properties.

Correlations between strength and quantitative computed tomography measurement of callus mineralization in experimental tibial fractures

BACKGROUND

the evaluation of fracture healing in the clinic has not changed significantly during the past few decades, despite the development of modern tissue-imaging tools. Recent publications have reported significant and interesting associations between biomechanical properties and quantitative computed tomography data of fractures and grafts. We therefore studied the correlations between the strength and segmented quantitative computed tomography data of tibial diaphyseal fractures.

METHODS

forty male rats received a tibial-shaft osteotomy that was initially stabilized with either intramedullary nailing or external fixation. Evaluation at 30 and 60 days post-osteotomy included X-ray, quantitative computed tomography and bending testing. Quantitative computed tomography data were segmented by voxel density into soft callus (171-539 mg/cm(3)), hard callus (540-1199 mg/cm(3)) and cortical bone (≥ 1200mg/cm(3)), and volumetric bone mineral density was calculated.

FINDINGS

all fractures demonstrated pronounced formation of soft and hard callus tissues at 30 days post-osteotomy, and at 60 days the cortical bone volume was significantly increased with callus resorption. Bending strength correlated significantly and positively with fracture-site cortical bone volume and volumetric bone mineral density in the intramedullary nailed group in the early phase of healing.

INTERPRETATION

quantitative computed tomography was used to quantify characteristic secondary healing. The observed correlations indicate that biomechanically important mineralization can be measured by quantitative computed tomography in the early phase of healing in flexibly fixed fractures.